/***********************/
/* run.c 1.00          */
/* by Adam M. Costello */
/* <amc@cs.wustl.edu>  */
/*                     **************************/
/* Completely detaches itself from its caller   */
/* by forking, letting the parent terminate,    */
/* changing the child's process group ID to its */
/* PID, and closing all descriptors except 0,   */
/* 1, and 2, which are closed and reopened to   */
/* /dev/null.  Calls execvp() using the first   */
/* argument as the filename and the remaining   */
/* arguments as the arguments.                  */
/*                                              */
/* If the name by which run is called ends with */
/* a `d', run will print the PID of the child   */
/* process, in decimal, on stdout.              */
/*                                              */
/* The exit status is 0 if the fork succeeds    */
/* and 1 if it doesn't.  The fork won't even be */
/* attempted if there are no arguments.         */
/************************************************/


#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <sys/time.h>
#include <sys/resource.h>
#ifdef NO_SETSID
#include <sys/tty.h>
#include <sys/ioctl.h>
#endif


main(argc,argv)
int argc;  char *argv[];
{
  int pid, n, d;
  struct rlimit rl;

  if (argc <= 1) exit(1);

  pid = fork();
  if (pid < 0) exit(1);

  if (pid) {
    if ((*argv)[strlen(*argv) - 1] == 'd')
      printf("%d\n", pid);
    exit(0);
  }

#ifndef NO_SETSID
    setsid();
#else
    setpgrp(0,0);
    d = open("/dev/tty");
    if (d >= 0) ioctl(d, TIOCNOTTY, NULL);
#endif

#ifndef NO_RLIMIT_NOFILE
  if (getrlimit(RLIMIT_NOFILE, &rl)) exit(1);
  n = rl.rlim_max;
#else
  n = getdtablesize();
#endif
  for (d = 3; d < n; ++d) close(d);

  d = open("/dev/null", O_RDWR);
  dup2(d,0);
  dup2(d,1);
  dup2(d,2);
  if (d > 2) close(d);

  execvp(argv[1], argv + 1);
}